.boxsned{
    width: 100vw;
    height: 100vh;
    display: flex;
    /* 三段式 */
    justify-content: space-between;
    flex-direction: column;
    align-items: center;
}

.header{
    width: 100%;
    height: 50px;
}
.main{
    flex: 1;
    overflow:scroll;
}

.mainBox{
    width: 100%;
    height: 150px;
    float: left;
}
.mainBoxLeft{
    width: 20%;
    height: 100%;
    float: left;
    text-align: center;
    line-height: 150px;
}
.mainBoxRight{
    width: 80%;
    height: 100%;
    float: left;
    line-height: 40px;
}